Being overweight does affect your libido. But small changes can jump-start your sex drive.

According to a recent study conducted by Binks and his colleagues at Duke, up to 30% of obese people seeking help controlling their weight indicate problems with sex drive, desire, performance, or all three. Often, the latest research shows, these problems can be traced to physical conditions that co-exist with obesity.

"Medical conditions such as high cholesterol and insulin resistance [an early indicator of type 2 diabetes] do have the ability to impact sexual performance, which in turn impacts desire, particularly in men," says Andrew McCollough, MD, director of sexual health and male infertility at NYU Medical Center in New York.

Because both conditions can cause the tiny arteries in the penis to shut down, particularly when vessel-clogging fatty deposits begin to form, McCollough says impotence or erectile dysfunction is often the result.

"A man who has problems having an erection is going to lose his desire for sex in not too long a time," says McCollough.

Men aren't alone with sex problems caused by poor blood flow. Research shows overweight women's sex drive and desire are affected by the same problem.

"We are beginning to see that the width of the blood vessels leading to the clitoris [the area of the vagina most closely related to sexual response] in women are affected by the same kind of blockages that impact blood flow to the penis," says Susan Kellogg, PhD, director of sexual medicine at the Pelvic and Sexual Health Institute of Graduate Hospital in Philadelphia.

When this happens, says Kellogg, a woman's body is far less responsive, and a drop in desire is not far behind.

Complicating matters further for both sexes: The more body fat you have, the higher your levels of a natural chemical known as SHBG (short for sex hormone binding globulin). It's aptly named because it binds to the sex hormone testosterone. Doctors theorize that the more testosterone that is bound to SHBG, the less there is available to stimulate desire.

What can you do to improve your physical conditioning for sex? Plenty. Experts say losing as few as 10 pounds can often free up testosterone and almost immediately give a boost to your love life.